The prior art is replete with examples of devices for mobilizing the joint of a person's limbs.
U.S. Pat. No. 6,416,448 discloses a therapy and training equipment for constrained knee-joint movement with a lower leg accommodating arrangement, and a guiding arrangement, the arrangements being connected to one another via an articulated device, the guiding arrangement cooperates with the lower leg accommodating arrangement in such a way that, on a rotational movement of one of the lower legs, the other lower leg is constrained to move as a result of the knee-bending movement.
U.S. Pat. No. 4,930,497 discloses an apparatus provided for imparting passive motion exercise to a lower limb of a patient. The apparatus includes a base and a thigh support member having a pair of elongated parallel spaced-apart brace members pivoted at their respective first ends to the base. The other ends of the thigh support brace members terminate at a mechanical hinge. A lower leg support includes a pair of parallel spaced-apart brace members extending from the mechanical hinge. The base is provided with a slide surface for supporting the other ends of the brace members of the lower leg support while allowing for extension and retraction thereof. An electric motor is mounted to the lower leg support to drive the shaft such that the angular movement is provided between the thigh support and the lower leg support, whereby the angular speed is maintained constant when motor speed is constant.
U.S. Pat. No. 5,421,798 discloses an apparatus for evaluation of a limb of a test subject. The apparatus generally includes a pedal or grip to secure the distal end of the limb to the apparatus and a seat to secure the proximal end of the limb to the apparatus. A motor and transmission assembly is coupled to the pedal or grip to provide a controlled load to the distal end of the limb. The apparatus also includes a measurement and control system to determine the load to be applied, and to measure and compute the force on each joint of the limb while the controlled load is applied to the limb. The measurement and control system includes a force sensor, coupled to the pedal, the force sensor being capable of resolving force in at least two directions; a position sensor, coupled to the pedal; and a computer with control software, coupled to the force sensor and the motor, the computer including means for controlling the force exerted on the pedal or grip by the limb of the test subject and the force exerted on the pedal or grip by the motor and transmission.
U.S. Pat. No. 5,890,996 discloses a combined exerciser and physical fitness performance monitoring apparatus and related methods. The apparatus includes at least one fluid working device, such as a pneumatic ram, which serves to provide an adjustable load. The fluid working device is movable using an adjustable mount to vary the compression ratio and loading rate. The fluid working device is connected to a user interface, such as foot pedals or hand holds, using a connection linkage. The apparatus also preferably includes a load modifier which adjustably engages the connection linkage and allows the rate of mechanical loading to be varied. This construction allows a large range of loads and force rates to be achieved.
WO03004107A1 discloses an exercise apparatus, preferably for rehabilitative exercise, and comprising means for allowing resisted linear movement combined with resisted rotative movement of for instance feet of a user, not shown pedals being mounted on shafts (8) attached to a chain (11) extending around sprocket wheels (12-16) provided with first braking means (17), for instance a first electrical motor (17), connected to the chain (11) for exerting a variable resistance against movement to and from the chain with the pedals attached t hereto. The shaft (8) is adapted for rotation against the influence of second braking means, for instance a not shown second electrical motor for exerting a variable resistance against rotation to and from the shaft with the pedals attached thereto. The braking means may be mechanical.